Headerless heat exchangers that directly connect the heat exchanger tubes or plates to a manifold or tank that distributes and/or collects the working fluid to and/or from the tubes are know. Some examples of such constructions can be seen in WO 00/75591, EP 0 775 884 A2, and EP 1 139 052 A2. Each of these constructions involves a stack of flat heat exchanger tubes that have deformed tube ends that abut against each other to form bonded, sealed joints that eliminate the need for a header plate. The manifolds in these examples include straight side walls that abut side surfaces of the stacked tubes to form a bonded, sealed joint therewith. U.S. Pat. No. 6,012,512 discloses several additional example of such heat exchangers, with some of the examples differing from the foregoing examples in that their manifolds have corrugated or V-shapes side walls that engage correspondingly shaped surfaces on the ends of the tubes in the stack. Typically, the foregoing examples are bonded by suitable soldering methods, such as by brazing. Additionally, the flow path for the second fluid in all the foregoing examples is an open flow path, typically for air, rather than an enclosed flow path such as is provided by so called stacked plate heat exchangers, one example of which is shown in EP 0 992 756 A2 and which utilizes a header plate (15).
While the foregoing examples may perform well for their intended function, there is always room for improvement. For example, there is a continuing desire to simplify the assembly and manufacture of such heat exchanger, such as by allowing the tubes to be formed from pairs of tube halves such as in stacked plate heat exchangers , and/or allowing such constructions to be preassembled and held together for a suitable soldering method with a minimum or no additional holding fixtures required.